This invention relates to a plunger pump
Generally, in a plunger pump having a cylinder and a plunger slidably fitted therein, seal packings, such as V-packings, are mounted at an inner peripheral wall surface of the cylinder to prevent leaks of a fluid delivered by the plunger pump under pressure from a pump chamber located at the head of the cylinder through a clearance between the inner peripheral wall surface of the cylinder and an outer peripheral surface of the plunger. In this type of plunger pump, the problem that the V-packings would undergo deterioration due to heat generated by frictional engagement with the plunger which moves in sliding movement in the cylinder during operation has been raised. To obviate this problem, it has hitherto been usual practice to apply a lubricant, such as grease, to the V-packings. However, this solution has not been satisfactory, because it needs the use of a grease cup or other lubricant supply means and makes the construction of the pump complex. In addition, when some type of lubricant supply means is provided, it becomes necessary to check on the presence or absence of the lubricant in the supply means, and trouble occurs when the lubricant is mixed with the fluid which is delivered under pressure by the pump.